What is weather? Here are five definitions I found in online dictionaries.
- The state of the atmosphere with respect to wind, temperature, cloudiness, moisture, pressure, etc.
- The state of the atmosphere with respect to heat or cold, wetness or dryness, calm or storm, clearness or cloudiness.
- The state of the atmosphere at a given time and place, with respect to variables such as temperature, moisture, wind velocity, and barometric pressure.
- The conditions in the air above the Earth such as wind, rain or temperature, especially at a particular time over a particular area.
- The state of the atmosphere with regard to temperature, cloudiness, rainfall, wind, and other meteorological conditions.
These are passive definitions. If wind, temperature, etc. were constant and/or totally predictable, there wouldn't be much to talk about. I prefer the active definition I learned in eighth grade science:
The variations in the atmosphere resulting from unequal heating of the Earth.
Yes, weather is solar powered. For example, when one area gets too hot, a pressure imbalance develops and the wind blows to equalize the pressure.
Now, what is climate? Here are five online dictionary definitions.
- The composite or generally prevailing weather conditions of a region, as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds, throughout the year, averaged over a series of years.
- The average course or condition of the weather at a place usually over a period of years as exhibited by temperature, wind velocity, and precipitation.
- The meteorological conditions, including temperature, precipitation, and wind, that characteristically prevail in a particular region.
- The general weather conditions prevailing in an area over a long period.
- The general weather conditions usually found in a particular place.
I italicized two commonalities in the above. First, climate is essentially an average, the composite, prevailing, general weather usually observed. Yes, we expect cold and snow in a winter climate, but it is the actual cold and snow that makes it a winter climate.
Second, climate is local, for a particular region, place, area, or place. There really is no such thing as a global climate. The Sahara, the Arctic, and Des Moines all have significantly different climates, such that any further summation is pointless. About the only variable one can attempt to meaningfully average is temperature, and even variations in that are not binding on a specific area.
The "Global Warming" crowd seems confused on these points. They too often say in effect that a nebulous "global climate" drives local climate, which in turn drives the weather itself. This is completely backwards.
Even the "global climate" - whatever that is - is simply a compilation. The unequal heating of the Earth is what creates what we commonly call weather, not the average heating. The Earth's 23.5 degree tilt of its rotational axis vs. its revolutionary plane gives us seasons. Its slightly elliptical orbit varies our distance from the sun by a million miles or so. And of course its rotation gives us night and day. Unequal heating will always be, and the atmosphere will respond accordingly.